Connection invalidation

NOTE: THIS FEATURE IS CURRENTLY UNSTABLE!

By default, AutoSlave does not remember cross requests, whether a connection is down or not.

To prevent AutoSlave from trying to connect to databases which are known to be down, the "invalidation path" option can be used:

<?php
$databases['default']['default'] = array (
  'driver' => 'autoslave',
  'master' => array('master'),
  'slave' => array('slave'),
  'invalidation path' => 'sites/default/files',
);
?>

This will make AutoSlave store the information about not being able to connect, in the file 'sites/default/files/autoslave-invalidation-default.inc'.

AutoSlave's cron job will update the information in the file, when the connection is available again.